This invention relates to a pick box for releasably housing a cutter pick, with the box adapted in use, to be mounted on a rotary cutting head of a shearer drum for mineral winning operations, or of a rock culling head for underground roadway or tunnel driving operations, or also for mineral winning, or, for surface use, of a road planing machine as part of highway maintenance.
All boxes, whether produced as steel castings or forgings, have an aperture to receive the shank of a cutter pick, the aperture diminishing the material and hence strength of the box and thus unavoidably creating an area of weakness, and hence breakage in extreme cutting conditions eg when encountering a band of hard rock or when inadvertently striking a metal object such as a roof beam, strata anchor etc.
Furthermore, when considering round pick shanks and hence round box apertures, the setting angle applied to the box on the rotary cutting head to give the correct cutting attitude of the pick, adds to the vulnerability of the box. The introduction of a sleeve between the pick shanks and the bore aperture reduces further the section of the box material remaining. In addition, current developments in box design include xe2x80x9cwetxe2x80x9d systems, fed by internal watercourse bores; which bores again create structural weakness to the box.
Apart from wear, xe2x80x9cwetxe2x80x9d boxes are prone, in general to two failings:
1. loss of system pressure when boxes are broken below their water carrying bores, and
2. internal blockage from water home debris.
Whilst a rotary cutting head or shearer drum may have 50 or more pick boxes, the breakage of one or two boxes will not greatly impair the cutting efficiency and the practice is to continue the use of a rotary member with broken boxes until say a scheduled maintenance period is reached, because a broken box requires the broken box(es) to be burnt off, and a replacement box to be welded on, and as such operations are not allowed by law in UK coal, mines the rotary member must be removed from the mining or tunnelling machine and transported either to the surface or to a safe area, for welding.
Apart from the above problem, and as indicated previously a broken box exposes a water bore, so that, instead of the water flow being throttled by a relatively small diameter spray nozzle or discharge of a spray at the required area, large quantities of water are wasted by uncontrolled emission from an exposed bore, resulting in diminished, or ineffective flow to the remaining spray nozzles, as well as inconvenient deposit of water in the mining etc area.
A basic object of the present invention is the provision of an improved xe2x80x9cwetxe2x80x9d pick box.
Summary of a First Aspect of the Invention
According to the present invention, there is provided a xe2x80x9cwetxe2x80x9d pick box for releasably housing a shank of a mineral cutter pick, the box comprising:
(i) a body member, adapted in use to be secured to a rotary member, aid having a front end and a rear end (having regard to the directions of rotation of the rotary member, in use);
(ii) an aperture in the body member corresponding cross-section to that of the sleeve or of a shank of a cutter pick intended, in use, to be carried by the box;
(iii) at least one bore in the body member defining an internal water course connectable, at an inlet end, to a source of pressurised water;
(iv) a water discharge nozzle also housed in an aperture in the body member and connected to an outlet end of the watercourse;
(v) a hole intersecting the bore towards tie rear end of the box, and
(vi) a member insertable into, and removable from the hole and, in one embodiment, to permit water flow, and in another embodiment blanking-off the bore to prevent water flow.
Advantages of the Invention
By the provision of the alternative insertable members, one member, for normal operation with a non-broken box, to permit water flow and may carry a water filter eg a gauze, to prevent debris entrained in the water supply reaching the spray nozzle and blocking same.
Importantly, if a box breakage should occur, then the flow permitting member is removed and replaced by a blanking-off member, which blocks water flow aid hence prevents uncontrolled emission or discharge of water from a bore exposed by the breakage, thus maintaining the water pressure for the remainder of the spray nozzles.
Preferred or Optional Features of the Invention
The hole intersecting the bore is a tapped hole, with the insertable member having an external thread.
The insertable member in one embodiment carries a filter through which the water must flow to reach the spray nozzle.
The filter is a thimble shaped metal gauze located in a receiving recess of the insertable member.
The insertable member, of any form carries at least one scaling ring.
The aperture in the body member is hexagonal.
A tapped hole is provided at or towards a front end of the box, to receive a water spray nozzle.
The internal watercourse is defined by at least two linear bores intersecting at a side face of the box at a side chamber which is closed-off by a cover plate, which is removable to expose ends of the intersecting bores, whereby a rod may be inserted to clear debris blocking the bore(s).
Summary of a Second Aspect of the Invention
According to a second aspect of the invention, there is provided a rotary, mineral cutting head to which a plurality of pick boxes in accordance with the first aspect, are welded.